Specialized mass spectrometry analyses are provided to the laboratory and to other collaborating units. The emphasis of this work is split between identification of trace organic compounds isolated from biological sources and the mass spectrometry of biopolymers (e.g. peptides, proteins and oligonuceotides). A very close working relationship and collaboration is maintained with the Laboratory of Biophysical Chemistry, NHLBI, especially with the research into, and use of techniques for, mass spectrometry of macromolecules. The electrospray source on the JEOL SX102 instrument was enhanced by the addition of a camera which allows easy optimization of the spray during analyses. The capillary zone electrophoresis instrument continues to receive heavy usage from this laboratory and others in the Institute. This has also been interfaced to the electrospray source where its separation efficiency far surpasses that of traditional HPLC methods. As part of the macromolecule collaboration with LBC, NHLBI, routine use is made of a mass spectrometer especially set up for sequencing of protein digests. In addition, use is made of a Laser Desorption mass spectrometer in NCI and in LBC, NHLBI (Dr. Fales) for the analysis of proteins and protein digests as part of our expansion into biopolymer mass spectrometry. In the small molecule area, collaborative interest has continued in the identification of biologically active natural products, especially those of interest in AIDS research and treatment; several anticonvulsant plasma drug level studies have been completed in collaboration with NINCDS. Samples analyzed derive from many facilities and researchers.